Radio frequency (RF) diode sputtering has been used for the growth of giant magnetoresistive (GMR) metal multilayers. Control of the atomic-scale structure of the surfaces and interfaces within these films is critical for GMR applications. A systematic series of experiments have been conducted to evaluate the dependence of the magnetotransport properties upon the growth conditions (i.e. background pressure, input power) for NiFeCo/CoFe/CuAgAu spin valves during RF diode sputter deposition. By using computational fluid dynamics, plasma, molecular dynamics, and various Monte Carlo techniques, a multiscale modeling approach has investigated the atomic assembly events during film growth. Energetic metal atoms and inert gas ion fluxes are shown to have very strong effects upon interfacial structures. The insights gained have led to novel deposition strategy propopositions for interface morphology control.

A new fully three dimensional (3D) ballistic deposition simulator 3D-FILMS has been developed for the modeling of thin film deposition and structure. The simulator may be implemented using the memory resources available to workstations. In order to illustrate the capabilities of 3D-FILMS, we apply it to the growth of engineered porous thin films produced by the technique of GLancing Angle Deposition (GLAD).

Computer simulations are used to study ionized physical vapor deposition, with ionized magnetron sputtering of copper as the primary system of interest. The effects of sputtering-ion energy and sputtering-ion angular flux distributions on the evolution of sub-micron scale features during IPVD are explored using the EVOLVE simulator. Our goal is to develop semi- quantitative engineering relationships that accurately predict the trends in experimental responses to changes in operating conditions. A sticking- factor model is used to describe deposition by neutrals. The sticking-factor of incident Cu atoms can depend on arrival angle and energy. Copper ions can also become part of the growing film. Energy and angular dependent sputter yields for both copper and argon ions are taken alternately from MD simulation results and a semi-empirical model. Sputtered material is ejected from the surface, tracked through the gas phase, and allowed to redeposit. Redeposition is also modeled via a sticking-factor based approach. The redistribution of film material results in non-intuitive profiles and complex relationships between final profiles and process parameters such as sample bias and neutral-to-ion flux ratios.

A novel quasi-thermodynamic approach is suggested to simulate surface chemistry in III-V compound MOVPE. Blocking of free adsorption sites by methyl radicals is considered as the mechanism limiting the growth rate at low temperatures. This assumption has provided a good reproduction of experimental data on GaAs MOVPE in various types of reactor. The commercial computational fluid dynamics software CFD-ACE™ has been used to perform a detailed threedimensional modeling of AlGaAs and InGaP deposition in an AIX-200 horizontal reactor. The surface model has been incorporated into the code to obtain the growth rate and layer composition distributions over the substrate. Modeling results demonstrate a reasonable agreement with experimental data.

Metalorganic Vapor Phase Epitaxy (MOVPE) has emerged as the technique of choice for growing thin films and structures of group III-nitrides. The objective of this work is to address the optimal design of vertical rotating disk and stagnation flow MOVPE reactors in order to achieve film thickness uniformity over large area substrates. Gas inlets that preserve the axial symmetry and enable alternating feeding of the precursors through coaxial rings were studied. The growth of GaN films from trimethyl-gallium and ammonia was used as a typical example. A fundamental reaction-transport model of the MOVPE process including gas-phase reactions and gas-surface interactions has been developed. The model was validated through comparison with growth rate data obtained from both research-scale and industrial-scale reactors. Performance diagrams for industrial-scale stagnation flow and rotating disk reactors were developed by varying the reactor geometry and operating conditions to identify regions of uniform film growth.

The heat and mass transport model extended to describe silicon cluster formation in the gas phase is employed for a numerical analysis of SiC CVD in a commercial vertical rotating disc reactor. The growth rate is studied as a function of precursor flow rates varied in a wide range of values. It is found that the growth rate is limited by the gas mixture depletion in silicon atoms due to homogeneous nucleation. The secondary phase formation on the growing surface is analyzed. The SiC growth window depending on the precursor flow rates is calculated, and a significant effect of the homogeneous nucleation on the window width is found. The model predicts that the Si/C ratio on the wafer can considerably differ from that at the reactor inlet.

Magnetic tunnel junctions (MTJs) are promising candidates for applications in spintronic devices such as magnetic random access memories, read heads and sensors. Previous studies have revealed the critical influence of the chemistry and structure of the ferromagnet metal/alumina interface on both sign and magnitude of the tunneling current in MTJs. We have performed a detailed first-principles study of the structure and bonding at the cobalt/alumina interface in order to understand the relationship between magnetic properties, local bonding environment and cohesion at the interface. Both Al- and 0- terminated interfaces were considered and full geometry optimization of the structure was done by selfconsistent spin-polarized calculations within density functional theory and the generalized gradient approximation. We found that the relaxed atomic structure of the 0-terminated interface is characterized by a rippling of the Co interfacial plane, the average Co-O bond length being 2.04 Å which is within 5% of that in bulk CoO and it is characterized by the covalent bonding between the 0 2p and Co 3d orbitals. The Al-terminated interface contains Co-Al bonds with an average bond length of 2.49 Å compared to 2.48 Å in bulk CoAl and it is characterized by metallic behaviour of the first aluminium layer. As a consequence of different character of bonding, the cohesion at the O-terminated interface is stronger as that at the Al-terminated interface, the work of separation being equal to 6.35 J/m2 and 3.64 J/m2 respectively.

The family of materials bearing the skutterudite crystallographic structure have recently attracted interest because of their extra-ordinary electrical and thermal transport properties, as well as their peculiar magnetic qualities [1]. Particularly, the group of cobalt antimonide skutterudites has been referred to as electron crystals and phonon glasses. With the goal to prepare skutterudite thin films, laser ablation is unique in its capacity to transfer skutterudite target's complex composition untouched to substrates while providing an hype thermal beam that has a positive influence on thin film growth. We use a pulsed excimer laser at 193 nm to evaporate skutterudites targets in ultra-high vacuum and deposit thins films on silicon wafers and fused silica substrate. We have studied the composition and crystallographic structure of the deposits as a function of substrate temperature and target to substrate distance. Deposits are skutterudite policrystals of several hundreds nanometers. We investigated the electrical as well as the thermal transport properties of thin films having the desired phase and compare these with value reported for the bulk mono-crystals.

We have used the embedded-atom method (EAM) to perform molecular-dynamics (MD) simulations of iron films grown on Cu (111). The iron atoms were randomly deposited, one at a time, above the surface just within the force range of the nearest surface atom. The growth mode is discussed by following the iron film coverage for an incident-atom energy ranged from 0.5eV to 15eV. A transition from island to layer by layer growth is observed as a function of incident energy. The effect of deposition rate is also studied.

The nitrogen incorporation behavior in GaAs was investigated in the growth temperature range 500-600°C. It was observed that the temperature-dependence of the nitrogen incorporation exhibits two regimes. At 530°C, the nitrogen content x is a nonlinear function of the gas-phase composition indicating a surface-controlled reaction mechanism. The N composition varies slowly with 500°C < T < 560°C with an activation energy of 0.6 eV. For T < 560°C, N decreases exponentially with Ea= 3.7 eV, interpreted in terms of nitrogen desorption. In light of experimental results, we propose a surface kinetic model based on the competitive adsorption of group V precursors.

For diamond synthesis with gaseous reaction, crystalline materials such as Si and Mo were used as substrates. In this study, we used materials of noncrystalline oxide for substrates, for example, quartz glass.

We used unique apparatus for diamond synthesis, completely closed system, no reaction gas was introduced to the chamber and no reactant gas was evacuated from it.

Deposits were Identified as diamond with SEM, AFM and Raman spectra. With these results, we successfully confirmed our samples as diamond particles on quartz glass substrate.

Superconducting YBCO/YSZ/Hastelloy tapes or coated conductors were fabricated by combining ion beam assisted deposition (ILBAD) and magnetron sputtering techniques. The degree of biaxial alignment of the YSZ buffer layers and the epitaxial YBCO films was determined from x-ray pole figures and ø-scans. The best YSZ buffer layers had FWHFM δø= 7°- 10°. The corresponding YBCO tapes achieved a similar degree of biaxial alignment and high critical current density, Jc(77K,0T) = (0.9 – l.25)×106 A cm−2.

We have succeeded in the synthesis of strong Cu(111) textured films by means of the novel ion plating method(URT-IP). This URT-IP method combines the Cu deposition with the surface cleaning (self-cleaning). In the Cu film synthesis, the cations play a main role: the self-cleaning of underlying Cu seed and TaN barrier surfaces at the first stage of Cu deposition and the promotion of (111) texture. The two growth processes dependent on underlying materials cause the strong (111) orientation; the epitaxial growth on the same (111) oriented underlayer and the promotion of thermodynamically stable (111) texture on the amorphous underlayer. The in-situ Ar+ cleaning of underlayer surfaces by the URT-IP improves the (11) orientation to be much stronger. The URT-IP method is applied also to the synthesis of strong Pt(111) textured films with the same fcc system.

Titanium nitride (TiN) films were successfully deposited on ρ-type Si (100) and (111) substrates by atomic layer deposition (ALD) method at 450°C. In this ALD system, the TiCl4 and NH3 gases were supplied, separately and Ar purge gas was added between the source and reactant gases to suppress the direct reaction. The main purpose of this study is to investigate the properties of TiN film grown by ALD method. To investigate the growth mechanism, the growth model of TiN was suggested for the calculation of growth rate per cycle with Cerius program. The results of calculation by the model were compared with experimental values of the TiN film deposited by ALD method. TiN films deposited on Si (100) and (111) substrates were examined by TEM and showed the randomly oriented columnar structure. The thickness of TIN film deposited on Si(111) substrate was slightly thicker than that of TiN film deposited on Si(100) substrate. Chlorine content in both TiN films was below the detection limit of AES (<lat%). And the densities of TIN films deposited on Si (100) and (111) substrates were 4.85g/cm3 and 4.98g/cm3. which are higher than that of the films deposited by other conventional CVD methods.

We have investigated the effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous diamondlike carbon (DLC) thin films prepared by pulsed laser deposition. The amorphous carbon films were deposited in various atmospheres such as nitrogen and argon at different pressures. We used Raman spectroscopy and optical microscopy to study the bonding characteristics and microstructures of the DLC films. Nanoindentation measurements were carried out on various samples prepared under different conditions to study the effect of chamber pressure and atmosphere on the elastic modulus and nano-hardness of the films. It was found that reduced vacuum leads to softer amorphous carbon films. Amorphous carbon films prepared in higher pressures exhibit increased density of particulates, and significantly rough surface. The results were understood in terms of thermalization of the laser plasma due to increased possibility of collision.

For few years, we had been concentrated of developing completely closed diamond synthesizing system aimed for microgravity experiments. Recently we started the new method with graphite as carbon source. With this method, completely closed system is successfully performed.

In-situ gaseous species analyzed with gas chromatographic analysis and possible reaction model will be presented.

We report on study of a growth system upscaling from 2” to 4” using numerical modeling. The model applied involves heat and mass transfer computations combined with a self-consistent analysis of deposit formation on the reactor walls. General trends in SiC bulk crystal growth originated from upscaling are discussed in detail.

We have developed a vapor deposition method that produces a highly ionized transient plasma plume of metallic species in the presence of a low-pressure inert or reactive gas glow discharge. In this process, a transient electrical discharge is formed in a hollow-cathode by a pulse-forming network (PFN) which is triggered by a pulsed CO2 laser. Current pulses with peak currents of 100 kA and pulse widths of about 20 ms have been produced by the PFN. The effect of the PFN power input and the ambient gas pressure on the evaporated material yield is presented. These experiments also showed a higher evaporation rate of carbon in a nitrogen ambient than in an Ar ambient. Carbon films, with rates of deposition exceeding 18A per pulse that are uniform over a large area, have been deposited. The ionic content of the plasma, spatial distribution of ions, and plume expansion dynamics have been investigated by time-of-flight ion probe measurements and optical emission spectroscopy and are presented.

α-Alumina films are useful for high-temperature, wear, and semiconductor device applications because of their good oxidation resistance, high hardness values, and electrical properties. α-Alumina films have been previously synthesized using techniques such as chemical vapor deposition, sol-gel, physical vapor deposition, and plasma spraying. This paper presents an alternative approach for producing high quality dense α-alumina coatings using a flame-assisted process called combustion chemical vapor deposition (CCVD). This process is an open atmosphere technique that does not require the use of a reaction chamber. In this work alumina films were grown on YSZ at temperatures ranging from 900 to 1500°C. At lower temperatures only amorphous alumina was grown, but as the deposition temperature increased different alumina phases were formed. At 1100°C, a thin highly crystalline θ-Al2O3 coating was formed. At temperatures higher than 1100°C thick θ-Al2O3 coatings were deposited on the YSZ. Coatings were characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD).